While an electrical Engineering degree would help - it is not necessary. The problem with trying to take classes is stuff like circuit theory/design is also going to have prerequisites that you may not have. I don't know about that book you linked to.
I think you would be better off Googling "basic electronic circuits" - I am sure you will find something for free so that you can at least look at a circuit and know what is the power source, switch, resistors, etc. Then maybe check out the Madvapes "how to section" and check out some designs.
Actually, the mod you mentioned is, IIRC, just a 3.7v mod(it starts at 4.2v and drops until the battery is drained to where it won't operate effectively). All that is required is a Li Ion battery, a switch(rated to handle ~3A) and an atomizer connector( you can even get these with pre-soldered wires if you want. Then you just need a container - easiest is a flashlight body or a battery box - something that already has connections for a battery.
Modding is a blast and is addictive. I say build yourself a super cheapo 3.7v single battery mod, learn a little bit and work on your soldering skills and then dive right in to a variable voltage mod - they rock. If you have any trouble or questions there are always people around to help.
Good luck!